Method of making linings for casting mold cavities



ug. 29, 1933. l J, D ALLEY 1,924,267

METHOD OF MAKING LININGS FOR CASTING MOLD CAVITIES Original Filed Aug. 22, 1929 Patented Aug-l f M50 tory shapes are fo 55; `should be maintaine eyf Pittsbu n Johnpqu e Shoe l 1932.'.seriaindczaosa f Y y solaires. f l"foies-9156i` A This application, is afdivisiono'f myoriginal applicationV kSerial No.

`f 1929.- i z. The inventionrelates to casting moldsandits` object is to provide a novel and simple method of making a lining of low` thermal conductivity'for a partv of the wall or for the'entire wall ofza mold cavity to prevent chilling vthecasting andV whichlining shall be capable of resisting repeat- Ved.` heat shocks .without cracking, spalling, for breaking down andalso be strongand substan-` tialto withstand the wear andtear of :repeated casting operations. 4 In; practicing my `invention for making a' lining for a brake shoe mold I employ fused silicaV and 1 a 'refractory binder. A` typicalV composition which I have found satisfactory for making a lining for av brake shoe mold consists of `60% fused silica and 40% refractory binder. The refractory `binder may consist of 50% Kentucky 3 bau' may and 50% `Georgia. kamin. 'meV percentage of clays may vary from 15% to V50% with a corresponding change in the proportion of fused silica. I may also. use a percentage .of

25 silicon carbiderfor a part of the fused silicaV in a composition as follows: fused silica Y40%, silicon 'carbide 20%, Kentucky ball clay 20%, and Georgia kaolin 20%. The thermal conductivity of silicon carbide is it is not desirable t`o use more tha in substitution for fused silica.`

All materials should be ground or crushed tori pass through a relatively fine screen, depending upon the Vquality of the refractory desired.` `Of p each material I have lused approximately one-v half of 20 to l80 mesh and one-half of 80 mesh and liner to provide a compact aggregate and aY dense refractory with smooth face, without voids, and with enough relatively coarse aggregate kto make'a structurally strong body.V The material should be thoroughly mixed in a dry-pan, in a pug mill, or in any other suitable manner. The blocks or' sections or liners for lining in rwhole or in part the wall oft .45 formed from a w'et mix by molding or by press-` ing; or they may be formed fromV what is 'ccmf monly known as'a dry mix, which. contains about 7% of water, under pressure of as much as one ton or more per square inch. After the refrac-A rmed they are thoroughly dried to drive olf excess moisture,l and then they Y Vare heated. This I suicient to vitrify the binder without devitrifying the fused silica andthe temperature d until the binder is entirely n 25% `of it MAKING yLnwnwas l `INefAMoLn cAvITIEs Rgjasvsign'or The u v' i i z el.,y ,ail Corporal;

387,817, led August 22, i.

comparatively vhigh and i he mold cavity may be.

heat treatment shouldjbe and "Foundry, Company,

` vitrined, and followed by slow cooling depending4 upon thei'size 'and section `of the shapes.-.v For example, the` heat treatment I:may 'bei continued -in asuitable furnace fora period ofA about four Y to five hours until the i temperature has raised,V -to'- 2100f `F.; Yand then fforfabout" six. hours atl 2100" F.,- followed'by slow cooling Vin the furnace for Aabout twelvetoffteen hours." 'It is important that the firing` temperature should 4not :be Vcarried to a degree whichwould tend to devitrify'the fused silica an'd'change it intoa crystal,- line form sensitive to heat shocks `The* invention may be employed'for. makingf `a lining of` any dimensionsl and configuration for amoldformaking any kind of casting. I have` used-'the liningin; anl iron moldffor making .brake shoes-in which the wall of the was partly or entirely lined-with blocksfor sec- .l tions made in accordance with my .invention and in thefaccompanying drawingI lhave illustrated the lining vembodiedzin a selected type of shoe mold and referring to whichn Fig. 1` is a llongitudinal sectionalview of the mold inV which the wall of the mold cavity Ais principally but not entirely providedwith a re` fractory liningl4 Fig. 2 is a transverse sectio 2-2 of Fig. 1, and Fig. 3 is a longitudinal to Fig. 1 'showing the lmold cav lined with'l refractory materiall y n Referring .to the drawing, 4 is the cope and '5,l v isrthe drag ofthe mold, the cope being centered vand seated on the drag in any suitable manner and provisionbeing made for removing the cope 4from the drag at the conclusiorr'ofl the casting operation by any suitablefmeans. A pouring'y gate' is` provided at any desiredloca mold through which the molten meta into the mold cavityv 7iforme`d par .cope and partly inthe drag. Thetype'of brake `f shoe to be producediin the mold ofgEigs. 1 and...l A2'isa. cast viron shoe,;having its end portions vchilled and otherpart's lunchilled.. For this pur-v pose the. cope has vaV lining section 8 and `the' drag has a lining section 9 seated therein" to form thewall of themold cavity except at'the end` portions 10 which are formed by the metal ofthe Copeland drag.V `A reenforce r lthe lug strap 12 and lug core 13 are heldin place Aat the top Q of 'the inold`r cavity by a wire 14 passing throughthe vent openingsl `or in any other ,suitable mannergfIhe shoe cast" this mold will be Aunchilled except 'ati the ends which-Will be chilledl where th nal view :on the line sectional view similar ity Wall fully 79. moldcavity brake; 7.5..

tion iritheY n i l susv back 1'1 with in .mixing ,eornmin'utediused silica and alQCmd-y the mix into;shapes,alnd f varying the Shapes, and ,then

contacts'with the iron of lthe mold. The mold f of FigfB is the same aszthe mold of exeept that the lining sections 8 the ends: of; the mold cavity-:

The blocks orlseetions arev madejln any' vshape 9 else ferm required to form4 inpart or in whole etheewall of the rn'olcloavity in -an/ iron mold otherwise often referred toas a permanentmold or as fa repetition mold, The .,l'iningvpreventsgthe Aeast metal from ehillingfit does not crack iorlspall or loreakl down'under the `repeated heat shocks of repetitionoasting operations, `and iitvlis struc-fVY .turaly' strong and substantiA l :tor-withstand! the wear andrtear of repeated'casti'ng operations. l

have given herein exarnpl proportions, and. have alsov given ring periods and ltemperatures which have beengfound to. loev satisfactory inl producing lining shapes .fror.-usev in'ironmoldsV for `castinglbrake shoes; but I do notlimitlthe invention to thesefpartioularSpeciffications` because it Willzrbe apparentjto those@ may fbefvaried more I skiuedzin/the enthlt they or .lessto .'sut. different` ,jcondtions and `to make linings for cliferentmoldslin'viaccordane with described. I :have ,'also givenl the 'methodherein certain clayimaterialsWhich-1 considenmost Vdesirable for Y the purpose but other v materials producing the same orsequivalentresults `may be substituted. Y Y v Y i n 'Ifclai-m:l .i

lining fora Castingfmold avity whichlconsists ingY material, forming rshapes ata temperature `suiiieientv to'v vitri-fy Ymi Figs.v l and 2 Ang-material, forming *a temperature" sufoient to inmaterial but not-sufiientto devtrify the fused bonding` material', forming the esoi y.materials Land y1. The herein ,described method v'of makinga heat v-treating the ythe bonding material but not sueientto'deyit'- rify the fused silica.` l Y Y. v Y

V2. The Yherein cleseriloed` method of InalfiingraV f lining vfor afeasting mold cavity-which consists in mixing "comminuted fused silica and a bondthe mix into shapes and l*drying the shapesfheat treating vthe shapes at slow coolingy the* shapes.

siima, andl then 3. The herein -vitrify the `bonding j v .described method of making a.

lining forlgla 4easting `rnold cavity which leonssts` slow cooling the fshapesiorapproximately -t toLfiiteenInQurs.

mix into' shapes! heat treating the shapes'v` 4 continuing the Aheat treatment for `approximately six hours at 2l00 F., and then 4. The herein deseriliecl'methoduof malhngfaia, lining 3or la., `casting moldlcavity whioh= .;consists in mixing 6 0 -c,omminuted fusedv sileafandAOP/o refractory fbindereonsistingjof substantially 50 Kentucky ballclay and 450%* -Georgiarkaolin formingxthe mix; into :shapesand;drying the vContinuing.fthe heat `treatment for:approximatev ly six hours at 2100J F. andfthensloyv cooling fshapes, V`heat treating :,theishapes ,by ,xcaisirigitixev Y temperature in an oyen-to i2l00^v TF1 during@- Y period `of .approximately ffourxto five hourspand the' .shapesfrfor approximately twelve,ftov'ffliteen` t Y 

